Jacob-Wilk, D., Faculty of Agriculture, Kennedy Leigh Ctr. for Hort. Res., Hebrew University of Jerusalem, Rehovot 76100, Israel
Goldschmidt, E.E., Faculty of Agriculture, Kennedy Leigh Ctr. for Hort. Res., Hebrew University of Jerusalem, Rehovot 76100, Israel
Riov, J., Faculty of Agriculture, Kennedy Leigh Ctr. for Hort. Res., Hebrew University of Jerusalem, Rehovot 76100, Israel
Sadka, A., Institute of Horticulture, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Holland, D., Institute of Horticulture, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel

Maturing citrus fruit undergo pigment changes which can be enhanced by exogenous ethylene. In order to identify genes induced by ethylene in citrus fruit peel, we cloned the gene c-thi1. mRNA corresponding to c-thi1 increased gradually in the peel during natural fruit maturation and in response to ethylene. GA3 pretreatment reduced the inductive effect of ethylene. Levels of c-thi1 increased also in juice sacs but the effect of ethylene was much less prominent. c-thi1 is homologous to yeast and plant genes encoding for an enzyme belonging to the pathway of thiamine biosynthesis. The data suggest that thiamine is involved in citrus fruit maturation.